Spark plug



Dec" 18, 1928.

2 INVENTOR.

CharYes 'C. Campbell Patented Dec. 18, 1928.

UNITED mas lemme c. onnrrnnnnor wnsnmcron, "DISTRICT or cononnrn;

-SPABK PLUG.

nppumnminnd mama-1. sesame-1123320, 1 1

-Thisinvention 1min {ringsideslgned. primarily vfor, use in eonnection.1 with that type of internal eomhustion engines or motors provided.withrsookets ionithe reception of the spark plugs and miththese latterset in with respect totheoutenfaceof; the

engine.hlock, forexampleienginesor motors of the Knight type andztheinvention has for its object to,providqinatmanner as hereinafter ,setforth,- a spark iphugrsm'finm' structed and so arranged with; respecttth engine block. to overcome sparkin .onshort circuiting at the outerend of the ug under such conditions providing .for any 'eficientoperation of .the, engine onmotor.

1n the motors of ithe typeehaving the spark lugs set: in withirespeettothe outer face 0% the engine it'zirequently happens that shortcircuiting is .hadat'the outer end of theiplug, due .to thenearnessofthe engine block,which prevents the plugs firing inthecombustion chamber, andsto oyencome such objectionand .toiinoreaseutheefliciency of the engine is the aimioianspark plug, in

accordance with thisuinvention and to this end the inventionresldesiinnrxapgingmhe outer terminals of the plugs the desiredidls"tancefrornthe outer: face ofthe a 'ne block toIprevent spankingatstheiouterib of the plugs, under such imoditions "owercQmi-ng shortcircuiting with respect i to the, plugs.

Further iobjectszaof the inveatipn are to 1 provide, in a manneras-here'wafter set forth, a spark plug for the ,purposeereiermdto whichis simple initsiconstructiomand.an.

rangement, strong, admirable, thoroughly eflicient in itsuse,neadily1nstalled,and 1116K- pensive to manufacture.

With the foregoing and other. iobiects in s.

,end of the core 8 andalso from the inner end view the inventionconsists. obanovelconthat changes, variations and imodificatipns can beresorted to which fall withinnthe p g inner section 11 and an outersection 12,

scope of the claimshereunto appended. i

In the drawings wherein "like reference,

n nlarged scale, ofaspark plug'in accordance with this invention.

Figure 3 is a section on line i=4 Figure 2. iFlgure 4 is a fragmentaryview, in vertical section, ofa modified form of plug. Referring to ,tliedrawings in detail 1 generally indicates a metallic shelliformed ofranouteraportioni 2 and anninner portion The outer, portion 2 is of,igreatervouter and inner diameters than the portion 3, whereby thelatter is inset with respect to said outer portion 2. The inner portion3 is provided. with threads 4 for connecting the shell 1 to the engine.blockto securethe plugnin position. The inner face, of :the outer.portion2 is threaded, asat .5. The outer part of said portion 2 isenlargedand of polygonal contourns at,6, to facilitate the securing andremovingfthe shelllgto and from the engine block. :Formed integral, withthe inner, end edge oftheshell 1,,is the outer electrode i 7 l which isof .angleshaped con-tour sol astoextend towards the axis of the shell 1.i

.. j indersbetweenethe outer part 2 and inner part 3 of theshelljl.Thecore8 is fixedly.

, secured toqthesshell; lyby a -speripherally threaded flangedcollanorsleeve 9 which: engages with the thncadsoofthe shell 1. and has itsinner, end-edge .bearagainst the core ,8 wherebythe latter isfixedlyclamped to ,the shell 1.

Extending axially through the core 8, as

well as fixedly secured therwith is a central electrode 10 whichprojects from the inner ofjthe shcllland coacts with the outer electrode7. The central electrode 10 is of a lengthtoproject a substantialdistance from the engineblockto prevent sparkingahthe outer end of theplug to, overcome short, circuiting.

The central electrode 10 is formed of, an"

which is of greater diameter than the section 11. ,Theseotion 12 at itsinner {end is formed :with a lengthwise extending socket; 13 having athreadednvall with which engages the threaded outerterminal portion 14of the section 11. The section 12 between its transverse median and itsouter end is formed with an annular flange 15, and that part of thesection 12 exteriorly of the flan e 15 is threaded as at 16 forengagement liy an interiorly threaded cap member 17 to clamp a circuitwire connection, not shown, to the flange 15, whereby the centralelectrode 10 is electrically connected with a source of energy. The capmember 17 preferably is constructed of insulation material.

The core 8 centrally thereof, is formed with an elongated socket 18 anda mortise 19 at the outer end of the socket 18. The socket 18 extendsbelow the transverse median of the core. Seated throughout the socket 18and extending from the core 8 to the section 12 ot the central electrode10, is a sleeve 20 of insulation material which closely envelopes thesection 11 from the inner end of the socket 18 to the inner end of thesection 12. The mortise 19 is formed in the outer end of the core 8,seated in said mortise and extending from the core 8 to the flange 15 isa sleeve 21 of insulation and which snugly embraces the sleeve 20 andalso a part of the section 12 01 the electrode 10. The periphcry of thesleeve 21 is flush with the edge of the flange 15 and the latter bindsagainst the sleeve to fixedly secure it in position. The section 12 ofthe electrode 10 oinds against the sleeve 20 to secure it in positionand the periphery of the sleeve 20 is flush with the periphery of thatpart of the section 12 in which is formed the socket 13.

he modified form shown in Figure 4, is the same as that illustrated inFigure 2, with this exception that the outer sleeve of insulation,indicated at 22 is mounted directly upon the outer end of the core 8 anddoes not extend into a mortise, as the core indicated at 23 is notprovided with a mortise for the reception of the inner end of the sleeveOtherwise than that as stated the construction shown in Figure at is thesame as that referred to in connection with Figure 2.

The central electrode 10 is of materially greater length than the depthof the socket formed in the engine head in which the plug to be mountedand of such length with respect to the depth of the socket as to projecta substantial distance from the mouth of the latter to prevent a sparkinaction at the outer terminal of the plug with respect to the outer tacoof the engine head, under such conditions overcoming short circuiting,with respect to the plug, resulting in increased engine efficiency,therefore it is thoughtthe many advantages of a spark plug, inaccordance with this invention, can be readily understood, and althoughthe preterred embodiment of the invention is as illustratet, anddescribed, yet it is to be understood that changes in the details ofconstruction an be had which will fall within the scope of the inventionas claimed.

\Vhat I claim is:

1. A spark plug comprising a metallic shell provided with an outerelectrode, a core of insulation secured in the shell, a centralelectrode extending through the said core and projecting from the outerend thereof and formed with a flange adjacent to its outer end, a air ofconcentrically arranged sleeves of msulation interposed between theflange and the core, the inner ot the said sleeves having its inner endextended from the inner end of the outer sleeve and the outer end of theouter sleeve extending from the outer end of the inner sleeve.

2. A spark plug comprising a metallic shell provided with an outerelectrode. a core of insulation secured in the shell, a centralelectrode extending through the said core and projecting from the outerend thereof and formed with a flange adjacent to its outer end, apair ofconcentrically arranged sleeves of insulation interposed between theflange and the core, the inner of the said sleeves having its inner endextended from the inner end of the outer sleeve and the outer end of theouter sleeve extending from the outer end of the inner sleeve, saidcentral electrode formed of an inner and outer section connectedtogether, said inner sleeve having its outer end abutting against theinner end of said outer sec tion, and the said outer section extendingfrom said outer sleeve and having its flange abutting against the outerend of the outer sleeve.

3. A spark plug comprising a metallic shell provided with an outerelectrode, a core of insulation secured in the shell, a rentralelectrode extending through the said core and projecting from the outerend thereof and formedwith a flange adjacent to its outer end, a pair ofconcentrically arranged sleeves of insulation interposed between theflange and the core, the inner oi the said sleeves having its inner endextended from the inner end of the outer sleeve and the outer end of theouter sleeve extending from the outer end oi the inner sleeve, saidcentral electrode formed of an inner and outer section connectedtogether, said inner sleeve having its outer end abutting against theinner end of said outer section, and the said outer section extendingfrom said outer sleeve and having its flange abutting against the outerend of the outer slceve, and said sleeves having their inner ends seatedwithin the core.

In testimony whereof, I ailix my signature hereto. 7

CHARLES C. CAMPBELL.

